The present invention relates to new medical uses of morphinans such as naltrexone, nalmefene and their related derivatives. The present invention relates to Toll-like receptor 4 (TLR4) antagonist compounds, and pharmaceutical formulations thereof, and use thereof for prevention and treatment of autoimmune liver diseases including but not limited to autoimmune hepatitis and primary biliary cirrhosis.
In PCT publication WO 03/097608, we have described a number of new medical uses of opioid and opioid-like compounds, including naltrexone. In PCT publication WO WO2006029167, we have described a number of new medical uses of ethylene-6-desoxy-N-cyclopropylmethyl-14-hydroxydihydronormorphine) or nalmefene, a long-acting, orally available, potent narcotic antagonist with pure antagonist activity.
Recent advances in the research of neurodegenerative diseases of the central nervous system have revealed that the opioids may play a role in modulating the expression of inflammatory factors such as proinflammatory cytokines, free radicals and metabolites of arachidonic acid in microglia and in the mediation of immune-related neurodegeneration [Adv. Exp. Med. Biol. 402: 29-33 (1996); Mov. Disord. 12: 855-858 (1997)] and neuropathic pain [Hutchinson M R, et al. Eur J Neurosci. 28:20-299(2008)].
Autoimmune diseases are immune disorders characterized by T cell hyperactivity and B cell overstimulation leading to overproduction of autoantibodies. However, the pathogenesis of various autoimmune diseases remains to be elucidated. Toll-like receptors (TLRs) are pattern recognition receptors which are part of human innate immune system that recognize and mediates early response to tissue injury, followed by activation of the adaptive immune system (Kesar and Odin 2014). Besides these exogenous pathogen-associated molecular patterns (PAMP), TLRs can also bind with damage-associated molecular patterns (DAMP) produced under stress or by tissue damage or cell apoptosis. It is believed that TLRs build a bridge between innate immunity and autoimmunity. There are five adaptors to TLRs including MyD88, TRIF, TIRAP/MAL, TRAM, and SARM. Upon activation, TLRs recruit specific adaptors to initiate the downstream signaling pathways leading to the production of inflammatory cytokines and chemokines. Under certain circumstances, ligation of TLRs drives to aberrant activation and unrestricted inflammatory responses, thereby contributing to the perpetuation of inflammation in autoimmune diseases. In the past, most studies focused on the intracellular TLRs, such as TLR3, TLR7, and TLR9, but recent studies reveal that cell surface TLRs, especially TLR2 and TLR4, also play an essential role in the development of autoimmune diseases and afford multiple therapeutic targets [Clin Rev Allergy Immunol. 47(2):136-47(2014)]. TLR4 is associated with hepatocytes and non-parenchymal cells, including Kupffer cells, myeloid dendritic cells, stellate cells, T-cells, NK cells, and sinusoidal endothelial cells. In recent years, some evidence suggests a likely mediating role of TLR-4 in the pathogenesis and progression of autoimmune liver diseases (AILDs) (He et al 2006; Longhi et al 2009; Mencin et al 2009). Monocytes from patients with PBC produce increased levels of proinflammatory cytokines such as IL-1β, IL-6, etc. when challenged with a variety of ligands, particularly those signaling through TLR4 and TLR5 (Mao et al 2005). Endogenous DAMPs are released subsequent to tissue damage. The ligands for TLR-2 and TLR-4 such as heat-shock proteins, HMGB1, hyaluronan, fibronectin, heparan sulfate and biglycan are produced to mediate sterile inflammation (Moreth et al 2014). The biological characteristics, signaling mechanisms of TLR2/4, the negative regulators of TLR2/4 pathway, and the pivotal function of TLR2/4 in the pathogenesis of autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, Sjogren's syndrome, psoriasis, multiple sclerosis, and autoimmune diabetes were recently reviewed by Liu Y, et al. [Clin Rev Allergy Immunol. 47(2):136-47(2014)]. Although TLR 4 is presumed to play the pivotal function of TLR2/4 in the pathogenesis of autoimmune diseases, direct evidence that TLR4 is implicated in AILD is still lacking. In this application, we disclose that TLR antagonists have demonstrated to be of potential in treating AILD.
Autoimmune liver diseases (AILDs), including but not limited to autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC), are all rare diseases but result in significant long-term morbidity and mortality (Dyson et al 2015). AIH is a chronic inflammatory disease of unknown etiology characterized by the presence of circulating autoantibodies, hypergammaglobulinemia, and necroinflammatory changes on hepatic histology, and a dramatic response to corticosteroid therapy (Makol et al 2011). Type 1 AIH is characterized by the presence of antinuclear antibody (ANA), anti-smooth muscle antibody (SMA), or both; Type 2 AIH is characterized by the presence of anti-liver kidney microsomal 1 (LKM1) and/or anti-LKM3 and/or anti-liver cytosol 1 (LC1) antibodies (Krawitt 2006; Makol et al 2011).
PBC is marked by the slow progressive destruction of the small bile ducts of the liver, with the intralobular ducts affected early in the disease. When these ducts are damaged, bile builds up in the liver (cholestasis) and over time damages the tissue. This can lead to scarring, fibrosis and cirrhosis. Most of the patients seem to have anti-mitochondrial antibodies (AMAs) against pyruvate dehydrogenase complex (PDC-E2), an enzyme complex that is found in the mitochondria (Mencin et al 2009; Testro et al 2009). Overlapping presentation has been observed with AIH and PBC.
Both AIH and PBC are of unknown cause, reflecting a complex interaction between triggering factors (e.g., innate immunity), autoantigens, genetic predispositions and immunoregulatory networks. Steroid/immunosuppressives combination and steroid/ursodeoxycholic acid (UDCA) are respectively frontline therapies for AIH and PBC. A lack of effective and safe drugs is the main drive for innovative novel therapy.
Concanavalin A (Con A), as a T-cell mitogen, causes acute hepatitis by T-cell activation (Tiegs et al 1992; Sass et al 2002; Shen et al 2014). In addition to the infiltration and accumulation of CD4+ T cells, Kupffer cells and natural killer T (NKT) cells, the Con A model is associated with pro-inflammatory cytokines including IL-1β, IL-6, and IFN-γ. Consequently, Con A-induced hepatitis is considered a representative model of autoimmune hepatitis.
Con A-induced hepatitis in mice in which mice are immunized with 2-octynoid acid coupled to BSA/OVA (2-OA-BSA/OVA) is considered excellent models of AIH (Xu et al 2011; Kawata et al 2013). This model is primarily T-cell dependent, driven by IL-23/Th17 pathway, in addition to IFN-γ. Con A hepatitis is sensitive to dexamethasone. High mobility group box chromosomal protein 1 (HMGB), an endogenous TLR4 ligand, is known to aggravate Con A-induced hepatitis, whereas anti-HMGB-1 protected mice from Con A hepatitis (Zhou et al 2012).